One option for working with imported bitmaps is to use Illustrator s Auto Trace tool to automatically generate vector lines and fills from the artwork. This works for simple drawings that can be traced easily. Or you can use the Auto Trace tool to start converting a bitmap to a vector object and finish up the job using Illustrator s drawing tools.
There are two adjustable properties for the Auto Trace tool. Oddly enough, they re not found in an Auto Trace dialog box or anything associated with the tool itself. Instead, you must select Illustrator (Edit) Preferences Type & Auto Tracing from the main Illustrator menu to open the Type & Auto Tracing section of the Preferences dialog box. Here you can define tolerance and gap settings.
Tracing tolerance can be defined on a scale of 1 “10, and tracing gap can be set anywhere from 0 to 2 pixels. A setting of 0 tolerance allows you to select very specific sections of an imported bitmap to convert to vectors, while a setting of 10 unleashes Illustrator to convert bigger chunks of the bitmap to vectors each time. A gap setting of 0 will stop conversion to vectors whenever there is a break in a line, while a setting of 2 will allow the generation of a continuous curve whenever a break of 2 points or smaller is encountered .
Note | The bottom line is that you'll end up experimenting with both tolerance and gap settings when you convert a bitmap using the Auto Trace tool. |
Figure 3-4 shows a drawing scanned with both high and low gap settings. The low setting is on the left, and the high setting is on the right.